The nature of this grant is to investigate ontogenetically and phylogenetically the mechanism(s) of adaptive immunity in ectothermic vertebrates and advanced invertebrates. One approach will be to define the role of temperature in regulating and modulating adaptive immunity in vivo in ectothermic vertebrates by using an in vitro model developed from mitogen studies on amphibian lymphocytes. Secondly, the ontogenetic development and distribution of mitogen-responsive cells will be delineated in anuran amphibians. Thirdly, the nature of lymphocyte polyclonal expansion will be investigated in two different groups of reptiles (turtles and lizards). A fourth approach will be to determine how closely the amphibian immune system mirrors the mammalian counterpart relative to distinct lymphoid cell types and their interactions. Specific projects will involve: 1) hapten sensitization (DNP) in Rana catesbeiana and Xenopus laevis, 2) induction of tolerance to SRBC and DNP in these same animals, and 3) quantitation of antigen-binding cells in Rana catesbeiana. The role of temperature, the ontogeny of mitogen responsiveness, the nature of lymphocyte polyclonal expansion, and a comparison of amphibian immunity with that of mammals will either confirm or disprove the phylogenetic conservation of these events during the evolutionary development of vertebrate adaptive immunity. Using earthworm coelomocytes, we plan to focus primarily on in vitro work confirming reports of cell division and studying rosette formation and morphological changes of cultured cells. A second approach will be to investigate for the first time the possible synthesis of bacterial agglutinins by earthworm coelomocytes. These studies will continue to emphasize the universality of immune responses, supporting the hypothesis that cell-mediated and humoral immunities underwent progressive evolution during development. BIBLIOGRAPHIC REFERENCES: Brown, B.A. and Cooper, E.L. 1976 Immunological dichotomy in the larval bullfrog spleen. Immunology 30: 299-305. Cooper, E.L. 1976. Immunity and neoplasia in mollusks. Isr. J. Med. Sci. 12: 479-494.